1. Field of the Invention
The present invention relates generally to process machinery, and more particularly, to a valve system that provides upstream isolation during purging and when not purging provides uninhibited recirculating fluid flow.
2. Description of Related Art
There are a number of devices in the prior art provided for controlling fluid flow. Fluid flow controlling devices are often used to control the rate of a desired fluid flowing through conduit for either cooling or heating processing machinery or articles being fabricated with the machinery. The fluid flows through the machinery, for either cooling or heating the machinery and any article produced thereby if desired, while the equipment is performing desired processing. However, over time the processing machinery, or conduit, or both, often become contaminated and cleaning of the processing machinery, or conduit, or both, and replacement of the fluid is needed.
One method of fluid removal and replacement may comprise first deactivating the processing machinery on both the supply and load sides. Once the processing machinery is deactivated, any required disassembly of the machinery or conduit to perform maintenance or replace portions of the conduit is performed. The fluid is then removed and the conduit or processing machinery may be cleaned if necessary, using known methods such as purging. The conduit and the machinery is reassembled, the fluid is replaced in the conduit and processing machinery, and the machinery is activated for processing.
An obvious disadvantage of the discussed method is that the processing machinery is deactivated while the fluid is being replaced and during cleaning of the conduit or machinery. With the processing machinery deactivated, processing is not performed and product output is potentially substantially reduced. Another disadvantage is that peripheral components provided to supply the fluid to the processing machinery, for example, may be adversely affected by the downtime of the machinery during the machinery or conduit cleaning.
A further disadvantage is that, often the fluid is maintained within a prescribed temperature range for maintaining the processing machinery at its optimal operating temperature. When the fluid is not circulating, the fluid tends to deviate from the prescribed temperature range. Thus, once the fluid is reintroduced into the processing machinery, there is an initialization time period wherein both the fluid flowing through the machinery and the machinery itself normalize toward the desired operating range. This further decreases the productivity time of the processing machinery and causes stress to devices for controlling the temperature of the fluid.
It therefore would be advantageous to provide a system that enables a purge process to be performed while simultaneously providing upstream isolation of the fluid flow and recirculating the fluid flow for maintaining the temperature of the fluid.
U.S. Pat. No. 5,505,219, to Lansberry et al., is directed to a supercritical fluid recirculating system for a precision inertial instrument parts cleaner. The disclosed system includes a fluid tight recirculating flow system including a parts holding chamber for holding parts to be cleaned. The fluid tight system directs supercritical carbon dioxide fluid flow across the parts being cleaned. A fluid recirculating cylinder has a first fluid port and a second fluid port connected in the flow system. A fluid piston is in the cylinder between the ports. A pneumatic cylinder has a further piston between a first pneumatic port and a second pneumatic port. A driving member is connected between the pistons for reciprocal movement caused by air from a source alternately introduced to the pneumatic ports to cause the fluid piston to pump fluid through the chamber and back to the recirculating cylinder. A plurality of one way valves are in the system to insure that the fluid pumped by the piston exhibits unidirectional flow through the chamber.
U.S. Pat. No. 4,958,659, to Dowdall, is directed to a pressuring and purging apparatus for pressurizing and purging an interior of an enclosure. The apparatus disclosed therein includes a purge valve for admitting gas to the enclosure at either a high flow rate or a low flow rate. A pneumatic control system for the purge valve includes a purge/power selector module. An enclosure pressure module and timing module are also provided. Each of the respective modules are mounted on respective faces of the purge valve body. The purge valve serves as a manifold for providing necessary connection of the control modules with each other and the enclosure interior for minimizing pipe connections.
U.S. Pat. No. 4,064,898, to Petersen et al., discloses and charge equipment that comprises a self-contained, portable apparatus that scrubs contamination from a sealed container and charges the scrubbed container with inert gas. The disclosed apparatus includes a housing for the apparatus, a gas reservoir, valves, and pneumatic logic for controlling the valves.
Although the devices disclosed in the above enumerated prior art references have improved features, there still exists a need for a valve system that provides upstream isolation and recirculating fluid flow, while simultaneously enabling a purge process to be performed.